I am wrong.
The discussion lead me to take a better look at the current documentation on Github. There's still no draft or any other type of standards proposal, just early design documents. But it clearly defines web client "scripts" as external modules to the webpage. So web client code is actually going to be decoupled from the markup. The markup will only import and reference these modules where necessary. The modules will be completely self contained, down to the DOM manipulation and management.
So this is in fact a tremendous improvement over current web development practices and goes well beyond just providing more programming languages to the web.
I was wrong.